Faculty of Sciences, Vrije Universiteit Amsterdam, De Boelelaan, Amsterdam, The Netherlands.
Biophys J. 2011 Jun 8;100(11):2829-38. doi: 10.1016/j.bpj.2011.04.029.
Plant photosynthesis relies on the capacity of chlorophylls and carotenoids to absorb light. One of the roles of carotenoids is to harvest green-blue light and transfer the excitation energy to the chlorophylls. The corresponding dynamics were investigated here for the first time, to our knowledge, in the CP26 and CP24 minor antenna complexes. The results for the two complexes differ substantially. In CP26 fast transfer (80 fs) occurs from the carotenoid S(2) state to chlorophylls a absorbing at 675 and 678 nm, whereas transfer from the hot S(1) state to the lowest energy chlorophylls is observed in <1 ps. In CP24, energy transfer from the S(2) state leads in 80 fs to the population of chlorophylls b and high-energy chlorophylls a absorbing at 670 nm, whereas the low-energy chlorophylls a are populated only in several picoseconds. The results suggest that CP26 has a structural and functional organization similar to that of LHCII, whereas CP24 differs substantially from the other Lhc complexes, especially regarding the lutein L1 binding domain. No energy transfer from the carotenoid S(1) state to chlorophylls was observed in either complex, suggesting that this state is energetically below the chlorophyll Qy state and therefore may play a role in the quenching of chlorophyll excitations.
植物光合作用依赖于叶绿素和类胡萝卜素吸收光的能力。类胡萝卜素的作用之一是吸收绿蓝光，并将激发能转移到叶绿素上。据我们所知，这是首次在 CP26 和 CP24 辅基天线复合物中对此相应动力学进行研究。两个复合物的结果有很大的不同。在 CP26 中，快速转移（80fs）发生在类胡萝卜素 S（2）态到吸收 675nm 和 678nm 光的叶绿素 a 之间，而在 <1ps 时，从热 S（1）态到最低能量叶绿素的转移被观察到。在 CP24 中，从 S（2）态的能量转移在 80fs 内导致叶绿素 b 和吸收 670nm 光的高能叶绿素 a 的种群增加，而低能叶绿素 a 仅在几皮秒内增加。结果表明，CP26 的结构和功能组织类似于 LHCII，而 CP24 与其他 Lhc 复合物有很大的不同，特别是在叶黄素 L1 结合域方面。在这两个复合物中都没有观察到类胡萝卜素 S（1）态到叶绿素的能量转移，这表明该状态的能量低于叶绿素 Qy 态，因此可能在叶绿素激发的猝灭中起作用。
